Exam 3 MC Question Bank

Question 1

Which of the following do not apply to “Uncouplers”?
A. Are “protonophores” that dissipate the proton gradient developed during respiration.
B. Transport Hydrogen Ions across the inner mitochondrion membrane.
C. Only acidic forms of uncouplers can cross the inner mitochondrial membrane.
D. Accelerate the oxidation of substrates because there is no phosphorylation of ADP to ATP.
E. Are usually lipid-soluble, weak, aromatic organic acids.

Answer 1

C. Outten says D is not necessarily true.

Question 2

Which of the following coenzymes and prosthetic groups of pyruvate dehydrogenase functions to be reduced by lipoamide?
A. TPP
B. Lipoic acid
C. CoA
D. FAD
E. NAD+

Answer 2

D

Question 3

Which of the following are not true regarding the functionality of Fatty Acid synthase?
I. Acetyl CoA is loaded at the KS thiol
II. ACP contains a Serine side chain
III. The priming reaction takes place at the AT site
IV. Step 1 of the reaction is a hydrolysis at the KS active site

Answer 3

C

Question 4

Which of the following is NOT a Metabolically Irreversible Reaction of the TCA cycle?
A. Reaction 3. Isocitrate Dehydrogenase
B. Reaction 1. Citrate Synthesis
C. Reaction 4. The α-Ketoglutarate Dehydrogenase Complex
D. Reaction 2. Aconitase

Answer 4

D. “You’ve got some grammatical mistakes. You ask about reactions but then list simple enzyme names as answer choices (not reactions). Be clear in your terminology to avoid confusion over the answers.”

Question 5

Which of the following enzymes is not involved in the conversion of pyruvate to acetyl CoA before entry into the citric acid cycle?
A. dihydrolipoamide acetyltransferase
B. pyruvate dehydrogenase
C. pyruvate translocate
D. dihydrolipoamide dehydrogenase

Answer 5

C

Question 6

Pyruvate Dehydrogenase is a multi enzyme complex. What is NOT an advantage that a multi enzyme complex like PDH would have over a series of single enzymes?
A. Substrate channeling to reduce intermediate side reactions
B. Increased rate of movement between enzyme active sites
C. Decreased rate of movement between enzyme active sites
D. Opportunities for coordinate control of all reactions carried out by the complexes
E. None of these

Answer 6

C

Question 7

What is the proper way to name this fatty acid? 18 carbons long, double bond between carbons 9 & 10.
A. 9:18Δ1
B. 18:1Δ9
C. 1:18Δ9
D. 18:9Δ1

Answer 7

B

Question 8

Which of the following is/are carriers that carry TWO electrons in the mediation of the electron transport chain?
I. CoQ
II. Fe-S clusters
III. FMN (flavin mononucleotide)
IV. FAD

A. I, II, and IV
B. II only
C. III and IV
D. I, III, IV
E. I, II, III, and IV

Answer 8

D

Question 9

Of the statements below, which is true about uncouplers?
I. Uncouplers are “protonophores” that dissipate the proton gradient developed during respiration.
II. Uncouplers transport electrons across the inner mitochondrial membrane.
III. Uncouplers are typically lipid-soluble, weak, aromatic organic acids.
IV. Only basic forms of uncouplers can cross the inner mitochondrial membrane.

A. I, II, III
B. II, IV
C. I, III
D. I, II, IV
E. All of the statements are true

Answer 9

C

Question 10

Which of the following enzymatic reactions of the tricarboxylic acid cycle have large negative ΔGo' values (rate-determining)?
I. Isocitrate Dehydrogenase
II. Acotinase
III. α-Ketoglutarate Dehydrogenase
IV. Succinate Dehydrogenase

A. I, II, IV
B. III, IV
C. I, III
D. II, III, IV
E. II, III

Answer 10

C

Question 11

Which of the following is false about The Citric Acid Cycle
A. The citric acid cycle produces 6 NADH, 2 FADH2, and 2 GTP per Glucose molecule.
B. NADH and ATP act as allosteric inhibitors of the enzymes involved in the TCA cycle.
C. The presence of insulin activates the pyruvate dehydrogenase complex by the phosphorylation of E1 by the PDH phosphatase. This serves to regulate the cycle by controlling the supply of Acetyl CoA
D. Pyruvate dehydrogenase converts pyruvate to oxaloacetate, which serves as the limiting substrate to the TCA cycle.
E. Certain intermediates of the citric acid cycle will act as precursors for amino acids, carbohydrates, lipids etc. These intermediates need to be replenished through Anaplerotic reactions.

Answer 11

D. “For answer C, a phosphatase cannot phosphorylate something so that answer is incorrect based on the way it is written.”

Question 12

The catabolism of which of the following amino acids does NOT yield pyruvate?
A. Alanine
B. Serine
C. Lysine
D. Threonine
E. None of the above; all of these amino acids are glucogenic

Answer 12

C

Question 13

Which of the following enzymes is not used in the full Urea Cycle?
A. Carbomyl phosphate
B. Arginase
C. Aconitase
D. Argininosuccinase

Answer 13

C. “Not all of the answers choices are enzymes so that creates confusion based on the way the question is worded.”

Question 14

Which of the following amino acids are exclusively glucogenic?
A. Aspartate, Tyrosine, and Isoleucine
B. Methionine, Threonine, and Valine
C. Tryptophan, Glutamate, and Glutamine
D. Aspartate, Asparagine, and Histidine
E. Methionine, Histidine, and Phenylalanine

Answer 14

D

Question 15

Which of the following the amino acids are both glucogenic and ketogenic?
A. Glu
B. Thr
C. Met
D. Leu
E. Lys

Answer 15

B

Question 16

Which of the following pairs of enzyme steps in the Citric Acid Cycle are both allosterically regulated to control the TCA cycle?
I. Fumarase
II. Malate
Dehydrogenase
III. Isocitrate Dehydrogenase
IV. Alpha-Ketoglutarate Dehydrogenase Complex

A. I. and II.
B. I. and III.
C. II. and IV.
D. III. and IV.
E. All of the above.

Answer 16

D

Question 17

\_\_\_\_\_\_\_assist in directing lipoprotein metabolism as well as help provide structure to lipoproteins.
A. Glycogen
B. Pancreatic lipases
C. Apoproteins
D. Malate-Aspartate Shuttle

Answer 17

C

Question 18

Which of the following statements is false about uncouplers?
A. Uncouplers transport proteins across the inner mitochondrial membrane
B. Uncouplers are typically lipid-soluble, weak, aromatic, organic acids
C. Uncouplers are “protonophores” that dissipate the protein gradient developed during respiration
D. Only acidic forms of uncouplers can cross the inner mitochondrial membrane
E. Uncouplers accelerate the oxidation of substrates because there is no phosphorylation of ADP to ATP

Answer 18

D

Question 19

Where do the final stages of aerobic oxidation of biomolecules occur in eukaryotes?
A. Nucleus
B. Golgi Apparatus
C. Rough ER
D. Mitochondria
E. Outside the cell

Answer 19

D

Question 20

Why is oxygen necessary in aerobic cellular respiration?
A. It is significant in creating oxaloacetic acid in the Kreb’s cycle.
B. It is necessary for glycolysis, which begins the process of respiration in cells.
C. It is the final electron acceptor in the electron transport chain.
D. It supplies the hydrogen nuclei necessary to create a proton gradient in the intermembrane space.

Answer 20

C

Question 21

What occurs during Step 3 of the PDH Complex?
A. Lipoamide converts Acetylaldehyde-TPP to form Acetyl-dihydrolipoamide.
B. TPP decarboxylates pyruvate and forms HETPP.
C. E2 transfers the acetyl group from Dihydrolipoamide adduct to HS-CoA to form acetyl- CoA.
D. A disulfide group of E3 oxidizes Lipoamide.
E. None of the Above

Answer 21

C

Question 22

Which of the following statements are FALSE regarding lipids:
I. Unsaturated fatty acids will have a higher boiling point, because they can pack together tightly.
II. Fatty acids are reserved for future energy needs in the form of triacylglycerols.
III. Triacylglycerols can be cleaved by phospholipases for use as chemical messengers during cell signaling.
IV. Glycerophospholipids are a large component of animal membranes are broken down into smaller pieces for absorption.
V. Steroids contain a nucleus structure consisting of four fused rings, and heme is an example.

A. I, II, IV
B. II, III, V
C. I, III, V
D. II, IV
E. I, IV, V

Answer 22

C

Question 23

Which of the following Ketogenic amino acids are able to be broken down to form the metabolite Acetoacetate:
I. Leucine
II. Tryptophan
III. Isoleucine
IV. Phenylalanine
V. Threonine

A. I and II
B. II and IV
C. I, II, and IV
D. I, III, and V
E. all of the above

Answer 23

C

Question 24

Which is false in β-oxidation of fatty acids
A. β-oxidation occurs in the mitochondrial matrix
B. β-oxidation occurs in three stages
C. β-oxidation degrades fatty acids 3 carbons at a time
D. Acyl-coA synthetase catalyzes the fatty acid to CoA thioesters in the first stage of β-oxidation.

Answer 24

C

Question 25

What is initially required for Fatty Acid synthesis to occur?
A. Malonyl CoA
B. Acetyl CoA
C. Pyruvate
D. Oxaloacetate
E. Palmitate

Answer 25

B. “This is poorly worded since malonyl-CoA is also required for all cycles of FAS. You need to phrase it more carefully if you want to make acetyl-CoA the only correct answer.”

Question 26

Which of the following is NOT formed by the catabolism of Glucogenic amino acids?
A. Fumarate
B. Alpha-ketoglutarate
C. Succinyl-CoA
D. Oxaloacetate
E. Acetoacetate

Answer 26

E.

Question 27

Which of the following is not true of BOTH Complex I and Complex II of the electron transport chain?
A. Complexes I and II are both starting points of the electron transport chain
B. Complexes I and II both utilize Flavin coenzymes as electron carriers
C. The end result of Complexes I and II is the reduction of Ubiquinone (Q)
D. Complexes I and II both have electrons enter the ETC by the oxidation of NADH
E. Complexes I and II both use protons (H+) from the matrix in reduction

Answer 27

D

Question 28

Some amino acids that break down into metabolites are ones that can be used for gluconeogenesis. These are called the Glucogenic amino acids. Which of the following is not one that is formed?
A. Pyruvate
B. α-ketoglutarate
C. Acetyl-CoA
D. Fumarate
E. Oxaloacetate

Answer 28

C. “Poorly worded, which of the following is not one what? amino acid? metabolite?”

Question 29

Which of the following statements about fatty acid (FA) synthesis is/are true?
I. FA synthesis occurs mostly in the cytoplasm
II. All two-carbon units of the fatty acid chain come from Malonyl CoA
III. FA synthesis ends with a palmitoyl group
IV. Mammals are only able to store up to 16-carbon long fatty acid chains
V. FA synthesis is activated by Epinephrine and Glucagon

A. I and III
B. I, III, and IV
C. I, II, III, and V
D. II, IV, V
E. III and V

Answer 29

A

Question 30

Which of the following is not one of the enzymes in the PDH enzyme complex?
A. Pyruvate dehydrogenase
B. Succinate dehydrogenase
C. Dihydrolipoamide dehydrogenase
D. Dihydrolipoamide acetyltransferase

Answer 30

B

Question 31

The two carbons of acetyl-CoA are the same carbons that are oxidized to CO2 in the initial turn of the citric acid cycle. True or False.
A. True
B. False

Answer 31

B.

Question 32

Enzymes in the Kreb's Cycle are located in the matrix of the mitochondria except for one enzyme which is located in the inner mitochondrial membrane. Which one of the following enzyme is located in the inner mitochondrial membrane.
A. α-ketoglutarate dehydrogenase
B. citrate synthase
C. succinate dehydrogenase
D.malate dehydrogenase

Answer 32

C

Question 33

What is the limiting substrate in the TCA Cycle?
A. Lipoamide
B. Oxaloacetate
C. Pyruvate
D. Acetyl CoA
E. a-Ketoglutarate

Answer 33

B

Question 34

In what part of the cell are Fatty Acid elongation/desaturation reactions most prevalent in?
A. Nucleus
B. Mitochondria
C. Cytosol
D. Membrane
E. Smooth ER

Answer 34

E

Question 35

Which of the following enzymes is responsible for converting Malate to Oxaloacetate in the Citric Acid Cycle?
A. Succinyl-CoA Synthetase
B. Fumarase
C. Succinate Dehydrogenase Complex
D. The alpha-Ketoglutarate Dehydrogenase Complex
E. Malate Dehydrogenase

Answer 35

E

Question 36

Which of the following do not occur in the mitochondria of humans?
A. The Citric Acid Cycle
B. Fatty Acid Oxidation
C. The Electron Transport
D. Chain Anaerorbic Respiration
E. Oxidative Phosphorylation

Answer 36

D

Question 37

There are mutations that can cause familial lipoprotein lipase deficiency, which reduce or eliminate lipoprotein lipase activity. This prevents the enzyme from effectively breaking down triglycerides in the bloodstream. What happens to the triglycerides that are attached to the lipoproteins?
A. The triglycerides are excreted as waste from the body.
B. The triglycerides accumulate in the blood and tissues, leading to inflammation of the pancreas, enlarged liver and spleen, fatty deposits in the skin, etc.
C. The triglycerides stay in the liver until they can be later digested.

Answer 37

B

Question 38

Which of the following describes the removal of amino groups from amino acids for metabolism?
A. Formation of α-Keto acids via transamination
B. Formation of ammonium salts via alkylation
C. Formation of aryl halides via substitution
D. Formation of imines via carboxylation
E. Formation of ammonia via oxidation

Answer 38

A

Question 39

Which molecules are activators to stimulate the Citric Acid Cycle?
A. NADH and ADP
B. ATP and NADH
C. Ca2+ and NADH
D. ADP and Ca2+
E. NAD+ and ATP

Answer 39

D

Question 40

Which of the following fatty acids has the lowest melting point?
A. 18 carbon monounsaturated fatty acid
B. 18 carbon saturated fatty acids
C. 18 carbon polyunsaturated fatty acid

Answer 40

C

Question 41

Which of the following statements is false?
A. The liver converts acetyl-CoA to Ketone bodies
B. Ketone bodies can be used by brain cells during starvation
C. Acetoacetate is the primary circulating form of ketone bodies
D. Acetoacetate is formed in the mitochondrial matrix
E. Acetone is formed when acetoacetate undergoes decarboxylation by β-elimination of CO2

Answer 41

C

Question 42

Proteins are constantly turning over. What benefits does protein turnover provide?
A. Allows damaged proteins to be eliminated
B. Allows amino acids to be stored as proteins then released as needed
C. Allows anabolism to occur faster, because catabolic hormones can be blocked
D. Both A & B
E. Both A & C

Answer 42

D

Question 43

Which of the following is FALSE regarding Electron Transport?
A. Five oligomeric assemblies of proteins are found in the inner mitochondrial membrane
B. Complex I-III contain multiple cofactors and are involved in electron transport
C. Complex IV is ATP synthase
D. Complex I contains NADH dehydrogenase and transfers electrons to Q
E. Complex III transfers electrons from Ubiquinol to cytochrome c

Answer 43

C

Question 44

Which of the following are enzymes used during the Urea Cycle that are found in the Cytosol?
I. Arginase
II. Carbamoyl phosphate synthetase
III. Argininosuccinase
IV. Ornithine transcarbamoylase
V. Argininosuccinate synthetase

A. II only
B. I and II
C. I, III, and IV
D. I, III, and V
E. V only

Answer 44

D

Question 45

In the electron transport chain, electrons flow from:
A. NADH to NAD+
B. NADH to O2
C. O2 to H20
D. COQ to FADH2
E. O2 to NADH

Answer 45

B

Question 46

Which enzyme is used in the glycogen phosphate shuttle system to convert glycerol- 3-phosphate to dihydroxyacetone phosphate?
A. a-ketoglutarate dehydrogenase
B. 3-phosphoglycerol dehydrogenase
C. flavoprotein dehydrogenase
D. aspartate aminotransferase
E. malate transferase

Answer 46

B

Question 47

What enzyme is the primary regulator of glycolysis?
A. hexokinase
B. phosphofructokinase
C. pyruvate dehydrogenase
D. carnitine transferase
E. glycogen phosphorylase

Answer 47

B

Question 48

You go in to your primary care physician for your annual check up. You went in to get blood drawn a week before to test all your levels and make sure everything is fine. At your appointment, your primary care physician tells you that your cholesterol is very high and she would like to reduce it. She prescribes bile salt/acid sequestrants that bind to bile acids and salts to lower your LDL-cholesterol. These drugs help eliminate the 'bad' cholesterol from your body, but can result in side effects. Which of the following are possible side effects?
A. Vitamin A deficiency
B. Vitamin D deficiency
C. Vitamin K deficiency
D. Gastrointestinal irritation
E. All of the above

Answer 48

E

Question 49

Which of the following lipid soluble molecules transports electrons from Complexes I and II to Complex III in the Electron Transport Chain and diffuses within the inner mitochondrial membrane?
A. FAD
B. Ubiquinone (Q)
C. NADH
D. Cytochrome C
E. FMNH2

Answer 49

B

Question 50

Following electron transport of H+ ions, where does the H+ buildup that drives ATP synthesis?
A. Intermembrane Space
B. Cristae
C. Outer membrane
D. Inner membrane
E. Matrix

Answer 50

A

Question 51

The liver lacks what enzyme, making it unable to oxidize ketone bodies?
A. Thiolase
B. Beta-hydroxybutyrate dehydrogenase
C. Hydroxymethylglutaryl-CoA synthase
D. Hydroxymethylglutaryl-CoA lyase
E. 3-ketoacyl CoA transferase

Answer 51

E

Question 52

All are true about uncouplers EXCEPT:
A. Uncouplers transport protons across the inner mitochondrial membrane
B. Uncouplers are typically lipid soluble, strong, aromatic organic bases
C. Both acidic and basic forms of uncouplers can cross the inner mitochondrial membrane
D. Uncouplers accelerate the oxidation of substrates because there is no phosphorylation of ADP to ATP

Answer 52

B

Question 53

Which absorption peak is often used in UV-vis spectroscopy to differentiate between types of cytochrome?
A. Alpha band
B. Beta band
C. Gamma band
D. Soret band

Answer 53

A

Question 54

In the Succinate Dehydrogenase complex, once the FAD prosthetic groups transfer electrons through the Iron-Sulfer clusters to Q. The Q cycle takes place. What does QH2 act as to continue electron transport?
A. Mobile lipophilic redox agent
B. Immobile hydrophilic oxidizing agent
C. Mobile hyrophilic redox agent
D. Immobile lipophilic redox agent
E. Mobile lipophilic oxidizing agent

Answer 54

A

Question 55

What molecule is oxidized by Complex II of the electron transport chain to produce electrons?
A. NADH
B. Fumarate
C. Succinate
D. Oxaloacetate
E. Ubiquinone

Answer 55

C

Question 56

What is the shorthand notation for this fatty acid? (18 carbons, 4 double bonds at 6, 9, 12, & 15)
A. 4:18Δ7,10,13,16
B. 18:4Δ6,9,12,15
C. 18:4Δ7,10,13,15
D. 4:18Δ6,9,12,15
E. 17:4Δ6,9,12,15

Answer 56

B

Question 57

The balanced quation for oxidizing one Palmitoyl CoA (16:0) requires _________ cycles
of beta oxidation and has a net yield of _______ ATP.
A. Two; 80
B. Seven; 106
C. Two, 106
D. Seven, 80

Answer 57

B

Question 58

Which of the following is the correct fatty acid nomenclature and is it essential or nonessential? (20C, 5 double bonds at 5,8,11,14,17)
A. 20:5Δ6,9,12,15,18 ; essential
B. 20:4Δ5,9,11,15 ; essential
C. 20:5Δ5,8,11,14,17 ; nonessential
D. 20:3Δ5,8,11 ; nonessential
E. 20:5Δ5,8,11,14,17 ; essential

Answer 58

E

Question 59

Which complex in the mitochondrial electron transport chain is the only complex to contain the citric acid cycle enzyme succinate dehydrogenase?
A. Complex I
B. Complex II
C. Complex III
D. Complex IV
E. Complex V

Answer 59

B

Question 60

What is the rate limiting enzyme in krebs cycle?
A. Pyruvate dehydrogenase
B. Citrate synthase
C. Malate dehydrogenase
D. Isocitrate dehydrogenase

Answer 60

D

Question 61

Which of the following is the fourth cofactor from the five reactions of Pyruvate dehydrogenase (PDH) along with its correct description.
A. NAD - this prosthetic group acts as an oxidant to convert reduced dithiols back to active oxidized disulfide forms
B. CoA - Is the fourth cofactor AND is the 2nd substrate
C. Thiamine PP (TPP) - prosthetic group that acts as an oxidizing agent in order to convert Acetylaldehyde-TPP adduct to oxidized acetyl-dihydrolipoamide form
D. FAD - this prosthetic group acts as an oxidant to convert reduced dithiols back to active oxidized disulfide forms
E. FAD - acts as a oxidizing agent to convert Acetylaldehyde TPP adduct to oxidized Acetyl- dihydropoline form

Answer 61

D

Question 62

In the first cycle of fatty acid biosynthesis there are four steps that continue over and over to create a 16 carbon palmitoyl. Put those four steps in the correct order:
A. Reduction of a trans-double bond
B. Reduction of a keto intermediate
C. Condensation of the precursors
D. Dehydration of a secondary alcohol

A. A, B, C, D
B. C, B, D, A
C. D, B, C, A
D. A, C, D, B

Answer 62

B

Question 63

Which of the following is false regarding the citric acid cycle?
A. Acetyl-CoA is the main common entry point.
B. Pyruvate made by glycolysis must be transferred into the mitochondria via pyruvate translocase.
C. Thioester bonds, which are formed to capture energy during metabolism, can be used to drive exergonic processes such as GTP formation.
D. The first metabolically irreversible step in the citric acid cycle involves isocitrate dehydrogenase.
E. Carbon dioxide is the final product.

Answer 63

D

Question 64

Which of the following is false regarding the citric acid cycle?
A. Acetyl-CoA is the main common entry point.
B. Pyruvate made by glycolysis must be transferred into the mitochondria via pyruvate translocase.
C. Thioester bonds, which are formed to capture energy during metabolism, can be used to drive exergonic processes such as GTP formation.
D. The first metabolically irreversible step in the citric acid cycle involves isocitrate dehydrogenase.
E. Carbon dioxide is the final product.

Answer 64

D. “Carbon dioxide is not the only final product. Answer is E is somewhat difficult to interpret.”

Question 65

Which of the following molecules is the original Ketone Body formed in the mitochondrial matrix?
A. Enoyl-CoA isomerase
B. Acetoacetate
C. B-hydroxybutyrate
D. Acteone

Answer 65

B

Question 66

Pyruvate Dehydrogenase (PDH) is a multienzyme complex. Which of these enzymes is NOT part of the complex?
A. Pyruvate dehydrogenase
B. Oxaloacetate
C. Dihydrolipoamide dehydrogenase
D. Dihydrolipoamide acetyltransferase

Answer 66

B. “Oxaloacetate is not an enzyme at all so that is not a good choice for this question (based on the way it is worded).

Question 67

Which of the following is paired incorrectly?
A. Flavin adenine dinucleotide (FAD) — Reduced by lipoamide and bound to E3
B. Thiamine pyrophosphate (TPP) — Bound to E1 and decarboxylates pyruvate yielding a hydroxyethyl-TPP carbanion
C. Lipoic acid — Accepts the acetyl group from from lipoamide and is covalently linked to a Lys on E2
D. Coenzyme A (CoA) — located on the substrate for E2 (dihydrolipoamide acetyltransferase) and accepts an acetyl group
E. Nicotinamide adenine dinucleotide (NAD+) — Reduced by FADH2 and is located on Substrate for E3

Answer 67

C. “For choice A, lipoamide does not directly reduce the flavin in E3, there is a Cys pair in the enzyme that mediates the process. So one could argue that choice is also incorrect.”

Question 68

Linolinate 18:3Δ9,12,15 is an essential fatty acid. How many Carbon atoms and C-C double bonds does it have?
A. 3 carbons with 9 double bonds
B. 18 carbons with 3 double bonds
C. 12 carbons with 3 double bonds
D. 18 carbons with 12 double bonds

Answer 68

B

Question 69

Which of the following steps of the Citric Acid Cycle allow for the entry/exit of amino acids?
I. Succinyl-CoA
II. Fumarate
III. Oxaloacetate
IV. Isocitate
V. Succinate

A. I, IV, and V
B. I, II, and III
C. I, and III
D. I, II, II, IV, and V
E. None of the above

Answer 69

B

Question 70

Which of the following statements is false about the Q Cycle?
A. Q is reduced to QH2 in a two-step reaction.
B. For every pair of electrons that pass through complex III to cytochrome c, 4 protons are translocated across the membrane.
C. Two molecules of cytochrome c are reduced and these mobile carriers transport their electrons to complex III.
D. A second electron is transferred to reduce the semiquinone to the mobile QH2.
E. In the first cycle QH2 is fully oxidized to Q.

Answer 70

C. “Answer E is hard to interpret. Do you mean the first half of the complete Q cycle or one full cycle? You regenerate a semiquinone on Q by the end of the first half of the cycle (so technically a QH2 is not completely oxidized by that point). The use of “first’ is the confusing part.”

Question 71

In the Fasting state, FA oxidation is favored as fats serve as fuel in place of glucose. There are Question three elements involved within the Fasting state that are effected by either being increased or
decreased. Which of the following is true concerning Epinephrine, Glucagon, and Insulin?
A. Epinephrine increases; Glucagon and Insulin decrease.
B. Epinephrine and Glucagon increase; Insulin decreases.
C. Epinephrine decreases; Glucagon and Insulin increase.
D. Epinephrine and Insulin decrease; Glucagon increases.

Answer 71

B

Question 72

Which of the following cofactors are matched correctly with their function in the conversion of pyruvate to Acetyl-CoA?
I. Thiamine PP (TPP) - decarboxylates pyruvate to form HETPP.
II. FAD - carboxylates HETPP to form a bond with the PDH complex.
III. Coenzyme A - oxidizes dihydrolipoamide to lipoamide.
IV. Lipoamide - oxidizes Acetaldehyde-TPP adduct to Acetyl-dihydrolipoamide.
V. FADH - reduces disulfides to dithiol form

A. I, III, and IV
B. I and IV
C. I, II, and V
D. I, IV, and V
E. I only

Answer 72

B. “For choice “V”, it should be FADH2. Are you saying that V is false because the reaction in E3 is the use of FAD to oxidize free dithiols back to a disulfide? Just clarifying. I agree that FAHD2 is not used to reduce disulfides in PDH (specifically E3). Instead the FADH2 formed from oxidizing free thiols is used to reduce NAD+ to NADH.”

Question 73

Which reaction in the Citric Acid Cycle is the only reaction where a C-C bond formation occurs?
A. Reaction 4: The Alpha-Ketoglutarate Dehydrogenase Complex
B. Reaction 1: Citrate Synthase
C. Reaction 5: Succinyl-CoA Synthetase
D. Reaction 8: Malate Dehydrogenase
E. Reaction 2: Aconitase

Answer 73

B

Question 74

What are some advantages of a multi-enzyme complex, such as pyruvate dehydrogenase?
I. Coordinated control of all reactions carried out by enzymes
II. Substrate channeling reduces intermediate side reactions
III. Decreases enzyme’s ability to be inhibited
IV. Increased rate of movement between enzyme active sites

A. I, III
B. I, II, IV
C. I, III, IV
D. I, II, III, IV

Answer 74

B

Question 75

In what order are the following compounds broken down and/or used to produce energy during vigorous exercise or extended starvation?
A. Glycogen→Ketone bodies→fatty acids
B. Ketone bodies→fatty acids→glycogen
C. Fatty acids→Ketone bodies→glycogen
D. Glycogen→fatty acids →Ketone bodies
E. Fatty acids→glycogen →Ketone bodies

Answer 75

D. “In the question, are you referring to “Glycogen” or “Triacylglycerol”? Glycogen is not broken down into fatty acids. It is broken down into glucose, which is used for energy by most tissues or released into the blood from the liver. It is true that glycogen may be consumed first before a large release of fatty acids from triacylglycerol but I’m not sure that is what you are asking.
Triacylglycerol is broken down into free fatty acids, which are then oxidized for energy in most tissues. In the liver free fatty acids are oxidized to acetyl-CoA which is then shuttled into ketone body formation rather than the TCA cycle (since the TCA cycle is being diverted for gluconeogenesis).”

Question 76

Which of the following substrates in the citric acid cycle is not coupled to the production of NADH?
A. Succinyl-CoA Synthetase
B. Malate dehydrogenase
C. alpha-ketoglutarate
D. Isocitrate dehydrogenase

Answer 76

A. “Be careful of your terminology. You have a mixture of enzymes and substrates in your list of choices but you specifically use “substrate” in the question. That could create a lot of confusion. You should replace “alpha-ketoglutarate” with “alpha-ketoglutarate dehydrogenase” or some other enzyme. Also, having three dehydrogenase choices and only one non-dehydrogenase choice kind of gives it away.”

Question 77

Which of the following enzymes is responsible for the removal and stereospecific re- addition of water from citrate within the citric acid cycle?
A. Succinate Dehydrogenase
B. Fumarase
C. Citrate Synthase
D. Aconitase
E. Alpha-Ketoglutarate

Answer 77

D

Question 78

Which of the following statements about lipoproteins are correct:
1. HDL transports cholesterol from the tissues back to the liver.
2. VLDL is digested to LDL and then to IDL.
3. Chylomicrons contain the apolipoprotein B-48, which activates lipoprotein lipase to hydrolyze component triacylglycerols.
4. VLDL, IDL, and LDL are synthesized by the liver to transport triacylglycerol and cholesterol from the tissues back to the liver.
5. Chylomicrons are synthesized by the intestinal mucosal cells to be released to the lymphatic vessels.
A. 2, 3, and 4
B. 1 and 5
C. 1 and 3
D. 1, 2, and 5
E. All of the statements are correct

Answer 78

B

Question 79

What type of chemical changes occur during fatty acid decomposition?
A. Oxidation and Lysis
B. Oxidation and Condensation
C. Reduction and Lysis
D. Reduction and Condensation

Answer 79

A

Question 80

Five oligomeric assemblies of proteins (complexes I-V) are associated with Oxidative Phosphorylation. What is true about these complexes?
I. Complexes I-V contain multiple cofactors
II. Only complexes I-III are involved in electron transport
III. Complex V is ATP synthase

A. I and II
B. II and III
C. III only
D. I only

Answer 80

C

Question 81

Which statements about Complex V (ATP Synthase) are correct?
I. ADP and Pi enter the F1 protomer in the L conformation and becomes ATP when the protomer is in the T conformation
II. ADP and Pi enter the F1 protomer in the O conformation and exit it as ATP when the protomer is in the T conformation
III. C subunits of ATP synthase form the rotor of the “turbine” that turns to synthesize ATP
IV. 10 protons are required per full turn of ATP synthase, making 3 ATP
V. Flow of electrons from the inner membrane space (outside) into the matrix (inside) causes rotation of the c-base turbine
A. II, III, IV
B. I, IV
C. II, III
D. II, IV, V
E. I, III, IV

Answer 81

E

Question 82

Which of the following transfers electrons from Ubiquinol to Cytochrome c? A. Complex I
B. Complex II
C. Complex III
D. Complex IV
E. Complex V

Answer 82

C

Question 83

Which of the following is NOT a cofactor used by pyruvate dehydrogenase?
A. Zn(2+)
B. Thiamine pyrophosphate
C. Lipoic acid
D. FAD
E. NAD(+)

Answer 83

A

Question 84

Ketone bodies are important fuel molecules during:
A. Digestion after a meal
B. Starvation
C. Fasting
D. Both B and C

Answer 84

D

Question 85

Which of the following are true regarding fatty acids? (select all that apply)
I. Saturated fatty acids contain C=C double bonds
II. Polyunsaturated fatty acids contain two or more C=C double bonds
III. Unsaturated fatty acids contain at least one C=C double bond
IV. Saturated fatty acids can be divided into monosaturated and polysaturated fatty acids V. Saturated fatty acids contain no C=C double bonds
A. I & IV
B. II & V only
C. II, III, & V
D. IV only
E. II & IV only

Answer 85

C

Question 86

What molecule is the final electron acceptor in the Electron Transport Chain (ETC)?
A. Ubiquinone
B. NADH2
C. O2
D. Cytochrome C Oxidase

Answer 86

C

Question 87

What are the two major forms of stored energy in vertebrates?
A. Starch and Glycogen
B. Starch and Triacylglycerols
C. Diacylglycerols and Glycogen
D. Triacylglycerols and Glycogen
E. None of the above

Answer 87

D

Question 88

Beyond the enzymes used in the beta-oxidation pathway, what additional enzyme(s) are required for the degradation of UFA?
A. Enoyl-CoA isomerase
B. 2,4-Dienoyl-CoA-reductase C. Triacyl-isomerase
D. All of the above
E. A and B

Answer 88

E. “A good topic but I think you make it too easy by having only a single choice that includes two answer. A student would zero in on that and think it was relevant. Maybe mix up the answer choices a bit more.”

Question 89

Which of the following statements about Cholesterol are true?
I. Cholesterol is a specific type of lipid called a steroid
II. Cholesterol is more flexible than other lipids due to the fused rings in its core
III. Cholesterol is a sterol because it contains an alcohol - a hydroxyl group - on carbon 3
IV. Cholesterol is a polar molecule
V. Cholesterol modulates the fluidity of mammalian cell membranes

A. I, II, and III are true
B. I, III, and V are true
C. II and V are true
D. I, IV, and V are true
E. II, IV, and V are true

Answer 89

B

Question 90

What is the limiting substrate in the Citric Acid Cycle?
A. Succinate
B. Oxaloacetate
C. Fumarate 
D. Malate
E. Citrate

Answer 90

B

Question 91

Electron transport along the Electron Transport Chain (ETC) is important for the function of the mitichondria as well as the production of energy for the rest of the cell. Which of the following statements on electron transport is false?
A. The two systems used to shuttle NADH across the inner mitichondrial membrane for electron transport are the Malate-Aspartate Shuttle and the Glycerol Phosphate Shuttle.
B. The transport of H+ ions across the intermembrane space is couple with electron transport. This leads to a buildup of the H+ ions in the Intermembrane space that helps drive ATP synthesis.
C. Cytochrome Cis peripheral heme protein on the outer face of the inner membrane that is used to transport electrons from Complex III to IV.
D. Ubiquinone is lipid soluble molecule. When it diffuses through the lipid bilayer it accepts electrons from Complexes II and III and passes them on to Complex IV.
E. Electrons enter the ETC two at a time through the oxidation of succinate in Complex II or by NADH in Complex I.

Answer 91

D

Question 92

What is the main product/outcome formed in the first cycle of the Q cycle?
A. QH2
B. Both e- go to the heme bL.
C. Q migrates to a Qo site again.
D. Semiquinone
E. Both e- go the cytochrome c1.

Answer 92

D. “I would just add that the semiquinone in question is reformed on Q by the end of the first half of the Q cycle (as opposed to a generic semiquinone somewhere).”

Question 93

Which of the following enzymes is involved in substrate level phosphorylation in the Citric Acid Cycle?
A. Citrate Synthase
B. Alpha-Ketoglutarate Dehydrogenase
C. Phosphoglycerate Kinase
D. Succinyl-Coa Synthetase
E. Phosphofructokinase-2

Answer 93

D

Question 94

During the generation of the proton-motive force:
A. the pH of the mitochondrial matrix decreases and the pH of the intermembrane space increases
B. the pH of the mitochondrial matrix decreases and the pH of the intermembrane space decreases
C. the pH of the mitochondrial matrix increases and the pH of the intermembrane space increases
D. the pH of the mitochondrial matrix increases and the pH of the intermembrane space decreases
E. the pH of the mitochondrial matrix increases and the pH of the intermembrane space remains the same

Answer 94

D

Question 95

During aerobic exercise the body attempts to produce as much energy as it can by generating ATP. Muscle contractions are a clear sign of activation of the Krebs Cycle, an ATP generating pathway. Which of the following are activators of this pathway?
A. ADP & NADH
B. ADP and Ca2+
C. ATP and Ca2+
D. NADH and ATP
E. NAD+ + ATP

Answer 95

B

Question 96

Which component of lipoproteins is responsible for its structure and directing lipoprotein metabolism by interacting with other proteins?
A. Apoproteins
B. Cholesterol
C. Cholesteryl esters
D. Phospholipids

Answer 96

A

Question 97

From the Citric Acid Cycle, how many NADH and FADH2 are produced per 1 Acetyl- CoA?
A. 2 NADH, 1 FADH2
B. 4 NADH, 2 FADH2
C. 3 NADH, 1 FADH2
D. 6 NADH, 2 FADH2

Answer 97

C

Question 98

Which of the following is an essential checkpoint that regulates the citric acid cycle?
A. Citrate Synthase
B. Isocitrate Dehydrogenase
C. α-Ketoglutarate Dehydrogenase Complex
D. All of the above
E. None of the above

Answer 98

D

Question 99

Which of the following is FALSE regarding the Pyruvate Dehydrogenase Complex?
A. The complex uses 3 cofactors (TPP, Lipoamide and FAD).
B. The complex has a Lipoyllysyl arm that swings between active sites.
C. The complex produces carbon dioxide, Acetyl-CoA, and NADH.
D. It is a multi enzyme complex made up of 3 enzymes.
E. It is used to regulate the Citric Acid Cycle.

Answer 99

A. “Not bad but a student could validly argue that CoA is a cosubstrate for the enzyme as opposed to a cofactor. It is consumed by the reaction (not recycled like the other cofactors). The precise definitions of cosubstrate, coenzyme, and cofactor are kind of murky and often debated in different biochemistry textbooks. It might be best to avoid a question that relies on only one interpretation of those definitions.”

Question 100

Which of the following sites do not control the rate of citric acid cycle?
A. Isocitrate Dehydrogenase
B. Pyruvate Dehydrogenase Complex
C. Aconitase
D. Alpha-Ketoglutarate Dehydrogenase Complex
E. Citrate Synthase

Answer 100

C

Question 101

Which statement is incorrect regarding the citric acid cycle
A. Acetyl groups are fed into the cycle and completely oxidized, but not necessarily immediately.
B. The electrons are saved in the form of reduced cofactors for Oxidative Phosphorylation.
C. Aconitase is a metabolically reversible reaction.
D. Citrate contains a tertiary alcohol that cannot be oxidized under biological conditions.
E. Succinate Dehydrogenase is a complex of several polypeptides and contains an FAD prosthetic group, which serves as the primary oxidizing agent.

Answer 101

B

Question 102

Which of the following fatty acids have the highest melting point?
A. CH3(CH2)10COOH
B. CH3(CH2)5CH=CH(CH2)7COOH
C. CH3(CH2)22COOH
D. CH3(CH2)18COOH
E. CH3(CH2)4(CH=CHCH2)2(CH2)6COOH

Answer 102

C

Question 103

The biomolecules FMNH2 and FADH2 each donate an electron to which coenzyme
A. NAD
B. Ubiquinone
C. NADP
D. Cytochrome C

Answer 103

B. “You may want to specify a particular protein that is bound to the flavin. Flavins can accept or donate electrons from lots of different substrates (they are widely-used cofactors for electron transfer reactions). I think the slide you reference specifically refers to the ETC?”

Question 104

Which of the following is the 2nd cofactor involved in the multienzyme complex, pyruvate dehydrogenase (PDH)?
A. FAD
B. Thiamine PP (TPP)
C. Coenzyme A
D. Lipoamide

Answer 104

D

Question 105

What is the most abundant steroid in animal membranes? A. Cholesterol
B. Cortisol
C. Estradiol
D. Diethylstilbestrol

Answer 105

A

Question 106

What enzyme is used to convert carbon dioxide and pyruvate into the intermediate, oxaloacetate, through an Anaplerotic Reaction?
A. Oxaloacetase
B. Pyruvate Carboxylase
C. Pyruvate Decarboxylase
D. Pyruvate Dehydrogenase

Answer 106

B

Question 107

Which of the following is NOT true about fatty acids?
A. As a general rule, as chain length increases, melting point increases
B. They are components of lipid bilayers in biological membranes
C. As a general rule, as the degree of unsaturation increases, melting point increases
D. They act as biological signals that control cell and tissue function
E. They act as energy stores in the form of hydrocarbon chains

Answer 107

C

Question 108

Identify the role of pancreatic lipase in the process of digestion of triaglycerides and phospholipids:
A. works with colipase to cleave triglycerides into smaller pieces
B. transports triglycerides due to their insolubility
C. emulsifies dietary lipids to make them soluble and make them better substrates for lipase enzymes
D. digests dietary phospholipids
E. traffics dietary lipids out of small intestine

Answer 108

A

Question 109

of the following is true?
I. The Citric Acid Cycle is not always a cycle
II. The Citric Acid Cycle can be used as an entry or exit point for other metabolites
III. The Citric Acid Cycle is useful in other pathways besides energy production
A. I Only
B. I and II
C. I and III
D. I, II, and III

Answer 109

D

Question 110

Atherosclerosis is an inflammatory response, thickening the walls of blood vessels and leading to plaque formation. The disease is attributed to an accumulation of \_\_\_\_\_\_\_\_.
A. IDL
B. LDL
C. HDL
D. VLDL
E. Chylomicrons

Answer 110

B

Question 111

How many net ATP/GTP can be made from one glucose molecule in a normal eukaryotic cell in the presence of both oxygen gas and DNP (an ETC-ATP synthase uncoupler)?
A. 30
B. 26
C. 4
D. 6
3. 2

Answer 111

C

Question 112

cytochrome c oxidase forms a transient radical at a \_\_\_\_\_\_\_ side chain adjacent to the heme a3-ligated O2
A. Serine 
B. Threonine 
C. Tyrosine 
D. Phenylalanine 
E. Tryptophan

Answer 112

C